Academic journal article Bulletin of the World Health Organization

The Rationale for Integrated Childhood Meningoencephalitis Surveillance: A Case Study from Cambodia/Justification De la Surveillance Integree De la Meningo-Encephalite Infantile: Etude Cas-Temoin Au Cambodge/Justificacion De la Vigilancia Integrada De la Meningoencefalitis En la Ninez: Estudio De Casos En Camboya

Academic journal article Bulletin of the World Health Organization

The Rationale for Integrated Childhood Meningoencephalitis Surveillance: A Case Study from Cambodia/Justification De la Surveillance Integree De la Meningo-Encephalite Infantile: Etude Cas-Temoin Au Cambodge/Justificacion De la Vigilancia Integrada De la Meningoencefalitis En la Ninez: Estudio De Casos En Camboya

Article excerpt

Une traduction en francais de ce resume figure a la fin de l'article. Al final del articulo se facilita una traduccion al espanol.

Introduction

Neurological infection is an important cause of death and disability in children in Asia. (1-4) Major vaccine-preventable etiologies of meningoencephalitis (ME) in Asia include Japanese encephalitis (JE) virus and bacteria such as Haemophilus influenzae type b (Hib), Neisseria meningitidis and Streptococcus pneumoniae. Public health initiatives to control these diseases are becoming more feasible with improved vaccine availability and affordability. (5)

However, in many Asian countries, the epidemiology and public health burden of JE and bacterial meningitis are poorly understood. Generation of disease-specific data for ME was spearheaded in some countries by the establishment of vertical disease-specific initiatives for control of JE, Hib and pneumococcal diseases (e.g. JE project at PATH, and the GAVI Alliance's Hib Initiative and pneumoADIP). However, the benefits of combining surveillance for meningitis and encephalitis are evident in terms of case identification, simplified logistics and systems, and the potential for more coordinated data analysis and consistent information to assist decision-makers in relation to vaccine introduction programmes.

This paper provides an example of development of an integrated ME surveillance system in Cambodia and, on the basis of this case study, presents the rationale and challenges for design and operation of such systems more generally in Asia.

System design for ME surveillance

A JE sentinel surveillance system was developed and embedded within the routine ME syndromic surveillance system in Cambodia in 2006. The sentinel system was designed so that it could provide a platform to incorporate laboratory testing for other central nervous system (CNS) infections in children.

The goal of the ME surveillance system in Cambodia is to assess disease burden due to neurological infection in children. Weekly reporting to the national level on the number of clinical syndromic ME cases and deaths is required from all district and provincial hospitals across the country. The syndromic ME surveillance is part of the national outbreak surveillance and response system.

The JE sentinel surveillance system was incorporated within this System. Six hospitals were chosen as sentinel sites from geographically diverse parts of the country. ME patients have epidemiological data gathered at these sites. When cerebrospinal fluid and blood are collected for routine case management, tubes are also collected for specific etiology testing. These additional samples are transported weekly to the National Institute of Public Health laboratory in the capital, Phnom Penh. Initially, only JE diagnostic testing by enzyme-linked immunosorbent assay (ELISA) was conducted. The system has been expanded recently and testing for vaccine-preventable etiologies of bacterial meningitis is now being added.

In the first year of surveillance, 47 of 275 (17.1%) ME cases reported from six sentinel sites were laboratory-confirmed as JE. The initial findings from the JE sentinel surveillance system are consistent with results of several previous research studies that have indicated approximately 20-30% of all acute encephalitis cases in Cambodia are attributable to JE virus infection. (6,7) With this preliminary data, an estimate of national ME incidence of 42.6 cases per 100 000 children aged less than 15 years and a minimum JE incidence of 7.3 per 100 000 children aged less than 15 years were calculated. Although many factors limit the precision of this estimate, the figure provides a useful estimate of childhood JE incidence in Cambodia.

Many challenges were confronted in the planning and implementation of the surveillance system. In the following section, we outline these challenges and the responses made. …

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